Of course, he accepted the contract. So you’re under no obligation to give him PTO. Totally reasonable for you to say “no.”
But, be aware about what he’s really asking under the surface, or you could lose him. He may not be “entitled”, as much as he’s starting a negotiation.
Is he effective enough to easily go get a salary position of equal pay somewhere else + get benefits (like PTO) that you don’t currently provide on top of that?